Fix a couple of coffee to js conversion blunders

lib/db.js

@@ -831,7 +831,7 @@ function getDueTasks(deviceId, timestamp, callback) {
           if (res[0]) {
             if (!task.fileType) task.fileType = res[0].metadata.fileType;
 
-            if (task.fileName)
+            if (!task.fileName)
               task.fileName = res[0].filename || res[0]._id.toString();
           }
 

lib/soap.js

@@ -501,7 +501,7 @@ function faultStruct(xml) {
 
 function fault(xml) {
   let faultCode, faultString, detail;
-  for (const c of xml.childNodes) {
+  for (const c of xml.childNodes()) {
     switch (c.name()) {
       case "faultcode":
         faultCode = c.text();
@@ -546,6 +546,7 @@ function request(data, cwmpVersion, warn) {
     }
   }
 
+  if (headerElement) {
     for (const c of headerElement.childNodes()) {
       switch (c.name()) {
         case "ID":
@@ -556,6 +557,7 @@ function request(data, cwmpVersion, warn) {
           break;
       }
     }
+  }
 
   for (const methodElement of bodyElement.childNodes()) {
     const methodName = methodElement.name();